I almost deleted your post because of the non-descriptive subject line. We get to many spammers and trolls here.

Rest time is not important. (Yes, Arnold said it was but science proved him wrong) Training volume and intensity are most important. ATP replenishes in a few minutes after working out. If you haven't fully replenished your ATP, you won't have the strength to push through the next set with the effort needed. If you're going to follow a program, follow all of the program. If you want to make more efficient use of your time, alternating movements does work. While you wait for one area to recover, you can work another. It's hard to do that while working whole body exercises like squats or deadlifts, however, throwing in some pullups between bench press sets is feasible.

Stu Ward
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Let thy food be thy medicine, and thy medicine be thy food.~Hippocrates
Strength is the adaptation that leads to all other adaptations that you really care about - Charles Staley
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Thanks TimD